Efficacy and safety of Moroccan and Turkish essential oils against Varroa destructor: varroacidal potency, locomotor activity impact, and mechanistic insights via molecular docking.

The ectoparasitic mite Varroa destructor is considered as a major threat to honey bees (Apis mellifera) worldwide, contributing significantly to colony losses. Conventional synthetic acaricides are increasingly ineffective due to resistance and the harmful residues they leave in hive products. This study evaluates the varroacidal activity and safety of essential oils (EOs) extracted from Moroccan (Thymus satureioides, Thymus pallidus) and Turkish (Origanum minutiflorum, Plantago major) plants. EO compositions were characterized by GC-MS, and their varroacidal activity was assessed via in vitro fumigation bioassays. While in silico analyses (molecular docking and dynamics) were conducted to identify bioactive compounds and elucidate their mechanisms of action, effects on locomotor activity were also examined. Thymol and carvacrol were identified as key active compounds, with molecular docking showing strong binding affinities to varroa odorant-binding protein (–7.1 and − 7.0 kcal/mol, respectively), supporting their observed bioactivity. The binary combination of O. minutiflorum and T. pallidus demonstrated synergistic effects, yielding the lowest LD₅₀ (0.845 µL/L air). Toxicity predictions indicated that most EO components posed low genotoxic and irritant risks. EO treatments significantly reduced bee locomotor activity compared to controls, though no differences were found among EO types. These findings highlight the potential of specific EOs and their combinations as sustainable and selective agents for varroa control, however, significantly reduced honey bee locomotor activity has been registered, suggesting potential sedative or sublethal neurotoxic effects.